Applied Mechanics and Materials Vols. 256-259

Abstract: To improve the wet soft silty sand bearing capacity, vibro-replacement stone column was used. Compared with the practical construction, this paper introduces the vibro-replacement stone column strengthening soft foundation. The principle of the construction, quality control, and inspection technology were discussed. Based on Drucker - Prager elastic-plastic model, different high wet soft foundation was simulated with the numerical analysis software. Results show that vibro-replacement stone column can significantly reduce the roadbed horizontal displacement. The displacement of the subgrade reinforced by stone columns decreases respectively 0.1, 0.2, 0.6, 2.3 cm than the other. If the subgrade is 4 m in height, the displacement reaches 0.2, 0.5, 0.7 cm when the length of stone column is 5, 10, 15m, respectively. To sum up, five - metre long pile is more economic and reasonable.

Abstract: In steam injection wells, the temperature of heat steam is very high and casing is heated during steam injection process, which has become the main reason of casing damage. Therefore, finite element model is very important to analyze the thermal mechanical coupling and casing damage in steam injection wells. Three-dimensional finite element model is investigated; geometry model is constructed with native and parasolid method in ADINA. The casing is modeled by native method and strata are modeled by parasolid method, casing is subtracted and merged with strata by Boolean Operation. Comprehensive loads are defined in structure model, and temperature load in thermal model. In thermal model, all materials are treated as heat conduction material. Thermal-mechanical coupling and casing damage are calculated with finite element model of thermal-mechanical coupling. According to the calculating results, the mechanism of casing damage is analyzed. Finally, some advice is proposed to the protection of casing in steam injection wells.

Abstract: The monopile foundation is usually subjected to vertical component (V), horizontal component (H) and moment component (M) in the design of offshore wind turbines.The three dimensional finite element numerical analyses were conducted to explore the failure mode of monopile foundation under monotonic loading. The failure modes under monotonic loading were obtained in different components. Soil produces different movement, and overall soil occurs wedge failure on both sides of monopile foundation.

Abstract: The corrosion risk of the immersed tunnel of the Hongkong-Zhuhai-Macao Bridge was evaluated by comparing the environment index with the durability index. The durability index was analyzed according to design, raw materials of concrete, concrete and construction. The results showed that the immersed tunnel could satisfy 120 years maintenance free design life-span if the concrete materials, design, and construction were controlled strictly.

Abstract: The damages of reinforced concrete pipe culvert appeared in use process brought a lot of problems. Investigated the pipe culvert damage characteristics, analyzed the causes of damages from load, structure stress and production, give the corresponding control methods.

Abstract: The paper made a simple study about the stress and nodal displacement theoretic analysis of different shape combined slabs by CATIA.It shows the following result in a visible way with 3D technology: First, the bearing capacity of combined slabs has a great relationship with their shape. Second, the vertical combined slabs can afford stress further surpass the horizontal combined slabs in the same condition and made by the same material.

Abstract: Based on the basic principles of structure reliability numerical analysis, the numerical simulation of the displacement and stress reliability of plane truss under vertical load was programmed with MATLAB. The failure probability of the most unfavorable structural vertical displacement and stress and reliable indicators were obtained through direct sampling Monte Carlo method, response surface method, response surface-Monte Carlo method and response surface-important sampling Monte Carlo method. It is found that calculation lasts longer since there are so many samples with Monte-Carlo method, higher accuracy and less calculation time can be achieved through response surface-Monte Carlo method and response surface-important sampling Monte Carlo method with fewer samples. The results of different numerical simulation calculations are almost identical and reliable, providing references to reliability analysis of complex structures.

Abstract: This study investigates the effectiveness of the damage detection methods depending on the data measured by strain and deflection sensors. The experimental work considers the damage detection by measured data only without the baseline data of intact structure. It is shown that the strain sensor cannot indicate the damage if the sensor doesn’t locate at the damage. But the deflection sensor provides the information on the damage from the deflected curve by collected data. The results are illustrated in experimental work.

Abstract: The long-term behavior of concrete structure shows that the main cause of deterioration is reinforcement corrosion. One of the most aggressive exposure conditions for concrete is marine environment. What is worse, the structure mixed with sea sand. Under these conditions, chloride-induced reinforcement corrosion rate could be very high, often leading to reduction of the service life. This paper investigates long-term corrosive beams in the above-mentioned cases. Chloride distribution is analyzed. From Fick’s second law, the parameters for chloride diffusion can be obtained. Then, the service life of the concrete structure is predicted via empolying probability analysis. The characteristics of randomness (concrete cover, diffusion coefficient, surface chloride concentration and so on) have been taken into consideration.

Abstract: Dynamic methods by structural vibration responses and system dynamic characteristic parameters are the main methods for structural damage identification. Based on the modal strain energy method and used unit location matrix instead of element mass matrix, modal kinetic method is proposed. Two kinds of typical damage condition were simulated and the results show that the method can reduce structural finite element model accuracy, calculate simply and realize the initial damage location.